State laws and insurance companies’ guidelines can differ so to find out exactly what will happen; you will need to contact your insurance provider. Your insurance company will likely investigate the claims and decide fault.

Usually when you rear-end someone you are found at fault so if he makes a claim against your insurance they will likely pay out on it. As for your own damages, again if you are found at fault for accident, even with him driving without a license and under the influence, then you would need to make a claim against your own collision coverage to get your damages taken care of.

If instead you insurance company deems that the accident was the other person's fault then you would need to see about placing a claim with his auto insurance liability policy or placing it with yours and let them subrograte the claim.

Even with the other motorist driving without a license and being arrested for a DWI hopefully his insurance would still cover damages he caused if he is at fault. Otherwise, your policy should cover it. That is the reason you pay for insurance and protection.